An Active Matrix Organic Light Emitting Diode (AMOLED) display, as a new-style displaying technology, has many advantages in terms of view angle range, picture quality, efficiency, cost, and the like, as compared to a Field Effect Thin Film Transistor (TFT) Liquid Crystal Display (LCD), and thus has a great potential for development in the field of the manufacture of displays.
The AMOLED can emit light since it is driven by the currents generated by the driving TFTs in the saturation state, however, the uniformity of the currents is poor and thus the uniformity of the luminance is always poor since different driving currents may be generated by the different critical voltages even if the same gray level voltages are inputted.
The conventional 2T1C circuit as shown in FIG. 1 only comprises two TFTs, wherein T1 is a switch transistor and DTFT is a driving transistor for a pixel. A scan line Scan turns on the switch transistor T1, and a data voltage Data charges a storage capacitor C; the switch T1 is turned off during the period of light-emitting, and the voltage stored on the capacitor keeps the driving transistor DTFT turned on; the turning on current drives the OLED to emit light. In order to achieve a stable display, it is required that a stable current is supplied to the OLED. The voltage control circuit has advantages such as a simple structure, a fast speed for charging the capacitor, and the like, while the voltage control circuit has a disadvantage that it is difficult to perform a linear control on the driving current, since the uniformity in threshold voltage Vth of DTFT is very poor due to the low temperature poly-silicon manufacturing process, and at the same time the threshold voltage Vth also drifts; even if same technical parameters are used in the manufacture of the TFTs, there are large variations in the threshold voltages Vth of the different TFTs, thus giving rise to the issues of poor uniformity in the light-emitting luminance and luminance attenuation in the driving circuit for light-emitting.